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June 2, 2011 -- More than 90% of children entering kindergarten in the U.S. have had most recommended immunizations, although coverage rates remain below target goals for most states, the CDC says.

The newly published vaccination coverage report for the first time includes state-by-state data on vaccination exceptions granted for medical, religious, or philosophical reasons.

More than half of the states providing vaccination information to the CDC had exemption rates of around 1% or less. Four states -- Alaska, Washington, Oregon, and Vermont -- had exemptions above 5%.

"Nationwide, the number of children who have not been vaccinated at all is less than 1%," CDC Director of Immunization Services Lance Rodewald, MD, tells WebMD. "This shows that parents and physicians understand that vaccination is the bedrock of child health efforts."

States That Met Target Goals

Forty-seven states and the District of Columbia provided data for the vaccine coverage report, published in the June 3 issue of the CDC's Morbidity and Mortality Weekly Report.

The government's target goals for vaccination among children entering kindergarten is 95% or greater coverage by 2020 for poliovirus; diphtheria, tetanus, and pertussis (DTP/DTaP/DT); measles, mumps, and rubella (MMR); hepatitis B; and varicella, the vaccine that prevents chickenpox.

The report revealed that:

Seventeen states reported coverage of 95% or more for each of four major vaccines: poliovirus; diphtheria, tetanus, and pertussis; measles, mumps, and rubella; and hepatitis B.

Just four states -- Georgia, Mississippi, Texas, and South Dakota -- had 95% or higher coverage for two doses of varicella vaccine. School-based chickenpox outbreaks led to a recommendation for a second varicella dose in 2006, but it appears that many children aren't getting the booster.

Mississippi reported less than 1% medical or non-medical exemptions, while Washington State had the highest percentage of exemptions, with 6.2% of children entering kindergarten with parent-signed exemption forms for one or more vaccines.

Philosophical Objections to Vaccines

The vast majority of the exemptions in Washington (4,515 of 5,015) resulted from parents who have philosophical objections to having their children vaccinated.

But Michele Roberts of the Washington State Department of Health says the number may be misleading because the state now allows parents to sign vaccination exemption forms when they register their children for school, so parents without the right documentation may be signing the forms for convenience.

A new state law that goes into effect in July will require a note from a licensed health care provider stating that caregivers have been counseled about the benefits and risks of vaccination.

"We think we've been seeing quite a few convenience exemptions along with the exemptions of conviction," Roberts tells WebMD.

But she says there is also evidence that low vaccination rates have contributed to disease in the state.

"Chickenpox outbreaks are a continual problem in our state and last year two infants died of pertussis [whooping cough]," she says. "In these cases there was not enough community protection to protect these infants."

Measles Cases on the Rise

Nationwide, there are also concerns about a rise in measles, largely driven by infections originating in other countries where measles rates are much higher.

Over the first five months of this year, 118 cases of measles have been reported nationwide, the highest number reported for the period since 1996. Forty percent of the cases required hospitalization.

About 90% of these cases were imported from other countries, including 34 cases among unvaccinated U.S. residents traveling abroad and 12 among foreign visitors to the U.S.

"Measles is much more common in other countries. France has a big outbreak right now," Rodewald says. "People who travel to other countries with an unvaccinated child may bring back measles and that child may infect other unvaccinated children."

That is what happened in San Diego in January 2008, when an unvaccinated 7-year-old infected in Switzerland spread measles to 11 other unvaccinated children.

While the current numbers are far below pre-measles vaccination levels, measles cases so far this year are already double that seen annually earlier in the decade, when the norm was around 60 cases a year, Rodewald says.